Automatic control and monitoring system for splice overlapping tolerance in textile ply

ABSTRACT

The present invention describes a system that enables the monitoring and automatic control of the tolerance in splice overlap of textile ply, through the identification of the overlap area ( 1   a ), identification and counting of textile cords ( 1   b ) in the referred overlap area, and the generation of a control signal for the remaining manufacturing equipment, based on parameters and criteria defined by the user. The system is composed of: an image acquisition sub-system ( 2 ) containing modules of lighting, of artificial vision and respective elements of support, fixation, conditioning and adjustment ( 3 ); a quality control computer program constituted by a module of morphologic image analysis for the detection and recognition of the overlap of the ply, detection and counting of cords in the overlap area, a module of support to the decision of acceptance/rejection of the ply based on parameters defined by the user and a module of interface with production equipment.

INVENTION FIELD

The present invention is included in the area of industrial control ofthe tyre manufacturing process.

PREVIOUS INVESTIGATION

The manufacture of tyres is the object of a very rigorous and demandingquality control that targets the guarantee of safety conditions sincethe physical integrity of people depends on their utilisation.

Under the present manufacturing conditions no tyre with any type ofdefect reaches the market since quality control is exhaustive, all tyresare tested, instead of statistical, by sample. This fact bearssignificant costs, since defects are not always detected at the initialmanufacturing stages causing a significant waste of finished product.

One of the aspects that are identified as the originator of defects isthe splice of the textile ply. A wrongly done splice consists of anoverlap with a reduced or excessive number of cords or textile thread. Asystem that does the counting of this number of threads will enable theelimination of a significant number of defects and contribute towards apronounced reduction of costs.

The present invention views the solving of this problem through anautomatic control and monitoring system of the tolerance of spliceoverlap in textile ply, which enables the identification of the overlaparea and counting of thread or cord fabric, and the generation of acontrol signal for the remaining manufacturing equipment.

State of the Technique

The continuous monitoring of textile ply splices used in the tyremanufacturing is not referred to in any patent of the knowledge ofinventors. The research carried out allowed some patents in the tyremanufacturing area to be identified, which are not concerned with themanufacturing stage within which the present invention is encompassed:EP 0 869 330 A2, Apparatus for testing tyre tread depth, where it isintended to determine the depth of the tyre's tread; U.S. Pat. No.4,892,609, Automatic material feeder in tire forming machine, which isencompassed by manufacturing and not by quality control; U.S. Pat. No.5,895,845, Method and gauge for measuring the tread depth of a motorvehicle tire, of a similar scope to EP 0 869 330 A2; U.S. Pat. No.3,997,783, Method for testing the adhesion between the rubber compoundand the cord fabric of a pneumatic tyre, which refers to the qualitycontrol of the adhesion between thread or cord fabric and the rubber.Since this deals with the analysis of the characteristics of acontinuous ply, research was carried out and some patents were found inthis area, but they do not contemplate the relevant aspects of thisinvention. Therefore, the patents EP 0 366 235 A1, Monitoring systemsand methods; EP 0 392 693 A2, Online texture sensing; U.S. Pat. No.5,256,883, Method and system for broad area field inspection of a movingweb, particularly a printed web; EP 0 757 245, Apparatus for detectingstreaky surface defects; NL 9 500 151, Method and apparatus forinspecting a web of material for defects, using the method in preparinga magazine reel in a reel changer, and reel changer provided with suchan apparatus; U.S. Pat. No. 4,277,178, Web element concentrationdetection system, refer to the analysis of the surface of plies,detection of elements, failures, textures, and not to the analysis inits thickness as is the case of the present invention. The patent EP 0329 889 A2, Method and apparatus for analysing a web of material,generates the profile of thickness of a ply or similar, but differs fromthe present invention because the present one detects and countselements, thread or cord fabric, instead of simply detecting theoccurrence of a different thickness. The patent U.S. Pat. No. 4,842,413,Apparatus for assessing the weld in belt layers for radial pneumatictires, analysis the alignment conditions of the surface of the metallicplies for radial pneumatic tyres but once again the analysis does notrefer to the thickness of the ply nor to the counting of the elementsbut to the alignment of layers.

In terms of commercial products, the inventors are unaware of theexistence of any product that solves the problem the present inventionintends to solve. Bytewise, an American company, commercialises aproduct that enables the monitoring and measurement of the thickness ofthe overlap splice of textile ply in tyre manufacturing. Nevertheless,it does not count the threads and the information it supplies, thicknessof the overlap has little interest, once the quality of the productdepends on the existence of an adequate number of cord fabric and notsimply of the thickness of the splice. The contrary may occur, where thethickness is adequate but the overlap does not contain the adequatenumber of threads, which is a source of defect in the final product. Inthese situations, the information of such a system may be incorrect ormisleading.

BRIEF DESCRIPTION

The present invention is constituted by: a sub-system of imageacquisition (2) containing the modules of lighting, artificial visionand respective elements of support, fixation, conditioning andadjustment (3); a computerised quality control program composed by amodule of morphologic analysis of image for the detection andrecognition of overlap of fabric ply, detection and counting of threadsor cords in the overlap area, a module of support to the decisionprocess of acceptance/rejection of ply based on the parameters definedby the user and a module for interfacing with production equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

Drawing 1 shows a typical example of an overlap splice of fabric plyused in tyre manufacturing.

Drawing 2 shows the configuration of the system in typical applicationscenario in the tyre industry.

Drawing 3 illustrates the sub-system of image acquisition.

DETAILED DESCRIPTION

The manufacturing of a tyre takes place in different sequential phases:Mixing, Preparation, Building, Curing and Quality Control. In thePreparation phase, the different rubber compounds mixed in the previousphase, Mixing, are used for the production of the components of thepneumatic tyre, amongst which is the textile ply.

This component has the function of guaranteeing the resistance of thetyre through the creation of conditions to contain the air introduced,guaranteeing the support of the intended load. Basically, a roll oftextile fabric composed of cords (1 b, previously prepared is guided tothe calender that will impregnate it with rubber (1 c). This ply islater on cut at 90° to the direction of the cord, in a width foreseenfor a certain tyre size. The various segments of the ply are splicedoverlapping a certain number of cords forming again a sole piece. Theply is rolled up for later usage.

In the calendering of textile fabric, two types of situations that causeimperfections in the overlap splices in the preparation phase of thetextile ply, and consequently, cause the non-approval of the tyres inthe quality control test, may occur:

-   -   Excess rubber on the ends of the fabric—Whenever necessary, in        the textile-cutting machine, the excess rubber on the ends of        the fabric is removed. If this operation is not done correctly,        the overlap is not perfect since in that area there will be, at        least in one of the segments, rubber without cords.    -   Failure of cords—In some situations, when the ply reaches the        textile cutter machine, the ply has some cord failures. In this        situation there will also not be a perfect overlapping.

If in the textile cutter machine, the overlap splicing process is notcorrectly adjusted, it may cause splices with an excessive or reducedoverlap space. In both cases, the splices will cause imperfections thatwill imply the non-approval of the tyre in the final quality controltests. A considerable part of the costs of the non-quality tyreproduction are consequence of these defective overlap splices of textileply.

The present invention describes a system that enables the identificationof the overlap area and the counting of textile cords fabric in thatarea and the generation of a control signal for the remainingmanufacturing equipment. The identification of the overlap area andcounting textile cords is done in both extremities of the overlapsplice.

The textile ply (4), after being spliced, is placed on a conveyor beltto be rolled up (S) in coils. Upon passing through the openings 5 a) and5 b) existent in the image acquisition module (2), the acquisition at arate of 50 frames per second of the two images obtained in bothextremities of the overlapping splice is done and are subsequentlydigitised and processed in real time. The sub-system of imageacquisition (2) enables the creation of environmental lightingconditions and protection of the exterior atmosphere that guaranteeconstant levels of contrast and colour for the gathered images. Inpractice, these conditions were achieved by adequately positioning thesources of light and equipping the sub-system with conditions tomitigate the internal reflection: internal barriers of light obstructionin the form of partitions (6) duly positioned and diaphragms forincandescence interception, painting with matt dark paint, bristlecurtain or similar material on the ply circulation slots. Thissub-system of image acquisition (2) may be constituted by lightingmodules (7) of coherent or incoherent light, in the form of incandescentor fluorescent lamps, LED or laser, or others. With respect to the lightcharacteristics it may be uniform, collimated or structured, with afixed or sweeping beam, and its wavelength be in the area of visiblelight spectrum, infra-red or ultra-violet. It may still be stroboscopic,which will enable the synchronisation with the detection process onbehalf of the module of artificial vision. Other intrinsiccharacteristics of light such as its polarisation may also be used. Thepositioning of sources of light in relation to the ply circulation slotwas another issue that was explored and used. This diversity views tomitigate the problems of internal reflection in the casing of the imageacquisition module as well as facilitating the identification of theoverlap area and of the cords in that area by the computerised qualitycontrol program.

The cameras (8) are of CCD type, colour and equipped with an opticsystem that enables an adequate zoom.

The system of support, fixation and adjustment of the image acquisitionmodule (3) was done by a worm screw controlled by an engine (9) thatpositions the cameras (9) on both extremities of the ply in asymmetrical way.

The acquired images are transferred to a computer, where the qualitycontrol program, in the morphologic analysis module, realises theoperations of splice detection and, in its presence, effectuates thecounting of the number of cords existent in the overlap.

Upon analysing the profile of the textile ply on the overlap splicearea, for this effect, only the splice area where there is overlappingof cords is considered. That is, on a splice where there is excessrubber on the ends of the fabric, both on the superior and inferiorpart, this overlap space shall not be considered as a splice. This meansthat a splice must be considered as good or bad, depending on the numberof cords only on the overlap area.

According to the specification of the manufacturing process, thestoppage of the splice system is undertaken when the number of cords isbeyond the pre-established tolerance limits, through a computer programthat supports the decision of acceptance/rejection of the ply, incommunication with an interconnection program with the remainingproductive equipment, usually done through a programmable logiccontroller, PLC. The quality control program is sufficiently versatileto enable a great diversity of stoppage criteria, both at individualsplices as well as of sequences of splice failures, so as to optimisethe quality control process in view of the specific production equipmentand of its manufacturing process.

1) An automatic control and monitoring system for splice overlappingtolerance in textile ply, characterised by being composed of: a)Sub-system of image acquisition (2) containing the modules of lighting,artificial vision and respective support, fixing, conditioning andadjustment (3) elements; b) Quality control computer program comprisedof the following modules: c) Morphological analysis of image for thedetection and recognition of the overlapping of textile ply, detectionand counting of threads or cords in the overlap area; d) Support to thedecision making process of acceptance/rejection of the ply based on theparameters defined by the user; e) Interconnection with productionequipment. 2) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the lighting module being comprised of: a) A source of light (7),coherent or incoherent; b) A casing to hinder the entrance of ambientlight; c) A background surface (10) to originate an adequate contrastfor the functions of identifying the overlapping region and counting ofcords. 3) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the lighting module has a uniform source of light orradiation. 4) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the lighting module is constituted by a fixed or asweeping beam. 5) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the lighting module is of collimated light. 6) Anautomatic control and monitoring system for splice overlapping tolerancein textile ply according to claim 1, characterised by the fact that thelighting module is of structured light. 7) An automatic control andmonitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised by the fact that the lighting moduleis of visible, infra-red or ultra-violet light. 8) An automatic controland monitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised by the fact that the lighting moduleis of stroboscopic light. 9) An automatic control and monitoring systemfor splice overlapping tolerance in textile ply according to claim 1,characterised by the fact that the lighting module is of polarisedlight. 10) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the lighting module is comprised of incandescent lamps,fluorescent lamps, halogen lamps, lasers in solid state, gaseous lasers,laser diodes or light emitting diodes (LED). 11) An automatic controland monitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised by the fact that the lighting modulehas one or more sources of light or radiation positioned frontally tothe textile ply or at an angle between −90° and +90°. 12) An automaticcontrol and monitoring system for splice overlapping tolerance intextile ply according to claim 1, characterised by the fact that thecasing that hinders the entrance of ambient light has a set ofpartitions (6) duly positioned to diminish the reflection of light lostin the walls of the referred casing. 13) An automatic control andmonitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised by the fact that the casing thathinders the entrance of ambient light has diaphragms for theinterception of incandescence. 14) An automatic control and monitoringsystem for splice overlapping tolerance in textile ply according toclaim 1, characterised by the fact that the casing that hinders theentrance of ambient light has, in the ply circulation slot, an externallight barrier in the form of curtains or bristle bars or any othersimilar material. 15) An automatic control and monitoring system forsplice overlapping tolerance in textile ply according to claim 1,characterised by the fact that the background surface (10) is inclinedat an appropriate angle, depending on the visual field of the referredcamera, to diminish the retro-reflection of the referred backgroundsurface onto the mentioned camera. 16) An automatic control andmonitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised for having a device for thedetection of the thickness of the textile ply, either mechanic,electronic, optoelectric or another type, which enables to synchronisethe release of the shutters of the video cameras with the passage of theoverlapping splice region. 17) An automatic control and monitoringsystem for splice overlapping tolerance in textile ply according toclaim 1, characterised by the fact that the background surface has onthe inner surface in the area of the ply circulation slot one or moremarks that limit the observation area facilitating its identification bythe computerised morphologic analysis program. 18) An automatic controland monitoring system for splice overlapping tolerance in textile plyaccording to claim 1, characterised by the fact that the module ofartificial vision has a video camera or cameras (8) of the type CCD,with the following characteristics: a) interline transfer, frame,complete frame or other architecture; b) arrangement of points with inline or on area sweeping; c) spectrum of sensibility to one colour or tovarious colours in the visible, in the infra-red or ultra-violetspectrum. 19) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the module of artificial vision has a camera or camerasthat function in synchrony with the lighting system of stroboscopiclight. 20) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the module of artificial vision has a camera or cameraswith polarising filters. 21) An automatic control and monitoring systemfor splice overlapping tolerance in textile ply according to claim 1,characterised by the fact that the support, fixation and adjustmentelement of the image acquisition module is comprised of a mechanicalassembly of an worm screw or other, manually activated or by an motor(9) controlled by the operator, or automatically. 22) An automaticcontrol and monitoring system for splice overlapping tolerance intextile ply according to claim 1, characterised by the fact that thequality control computer program has a morphological module of imageanalysis that enables the: a) Detection and recognition of theoverlapping of the textile ply; b) Detection and counting of cords inthe overlap area; c) Adjustment of detection in view of the colours anddimension of the ply, of the cords and of the rubber, by the operator orautomatically. 23) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the quality control program has a decision module ofacceptance/rejection of the ply that enables the user to define theparameters and criteria, as for example, the maximum and minimum numberof faults or patterns of the ply batches with certain sequences offaults. 24) An automatic control and monitoring system for spliceoverlapping tolerance in textile ply according to claim 1, characterisedby the fact that the quality control program has an interface modulewith the remaining production equipment that enables the interface witha programmable logic controller, PLC. 25) Utilisation of the automaticcontrol and monitoring system for overlapping splice tolerance intextile ply according to claim 1, in the tyre production industry.